Well off, better off:

well-off

این کلمه به طور کل به پول و مسایل مالی دلالت می کند. از این کلمه وقتی برای کسی استفاده می کنیم که نه ثروتمند بلکه دارای توان مالی تا اندازه ای باشد که مثلا دارای یک خا نه و یک ماشین باشد(نه ثروتمند و نه فقیر).

Well-off relates mainly to money matters. If you are well-off, you may not be rich exactly, but you have enough money to live well and comfortably:

By central European standards they are quite well-off They have their own flat and drive new cars.

well-off for

از این کلمه وقتی استفاده می کنید که بخواهید بگویید مقدار زیادی از چیزی دارید.

However, if you say you are well-off for something, this means that there are many of them:

We’re well-off for coffee shops in this town. There’s one at every corner in the High Street.

better-off

این کلمه صفت مقایسه می باشد و در مواقعی استفاده میشود که از نظر مالی مقایسه می کنیم.

The comparative form of this adjective is better-off which is used to talk about the varying degrees of wealth different people have:

We’re not as well-off as the Jones’s. They’re definitely better-off than we are. Just look at the way they dress!

To be better-off, as you suggest, Mariano, also has another meaning of being in a better situation and is used mainly in conditional patterns as follows:

If you’ve got heavy bags to carry, you’d be better-off taking a taxi.

It says on the sign that the motorway ahead is blocked. You’ll be better-off if you leave the motorway at this junction which is coming up now.

the better-off

این کلمه را برای مقایسه کردن گروه مردم استفاده می کنیم.

The better-off is sometimes used as a noun to describe a category of people, cf the rich / the poor:

The rich and the poor live side-by-side in this part of town.

The better-off should pay a higher rate of income tax, while those who are worst-off should pay no tax at all.